CN108218691B - Method for separating fatty acid and fatty acid methyl ester - Google Patents
Method for separating fatty acid and fatty acid methyl ester Download PDFInfo
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- CN108218691B CN108218691B CN201611199763.9A CN201611199763A CN108218691B CN 108218691 B CN108218691 B CN 108218691B CN 201611199763 A CN201611199763 A CN 201611199763A CN 108218691 B CN108218691 B CN 108218691B
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/42—Separation; Purification; Stabilisation; Use of additives
- C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation
Abstract
The invention relates to a method for separating fatty acid and fatty acid methyl ester, which comprises a step of allowing fatty acid in a mixture of fatty acid ester and fatty acid to crystallize, wherein the content of fatty acid in the mixture of fatty acid ester and fatty acid is more than 85%, preferably in the range of 85-95% based on the total weight of fatty acid ester and fatty acid. The invention also relates to the use of fatty acid esters for the separation of fatty acids. The method utilizes the fatty acid ester as a solvent, can quickly separate the fatty acid and the fatty acid ester, and obtains the high-purity fatty acid.
Description
Technical Field
The invention belongs to the field of grease processing, and particularly relates to a method for separating fatty acid and fatty acid methyl ester.
Background
As an important industrial raw material, the production and separation processes of fatty acids have a long history. The medium-chain fatty acid can be used for synthesizing caprylic/capric triglyceride, polyol ester and the like, is used for metal lubricants and personal care product skin moistening, and is also used for herbicides, bactericides in animal feeds, corrosion/rust inhibitors of antifreezing agents, mining flotation agents, formulas of creams and emulsions, raw materials of plasticizers and the like.
One method for producing the medium-chain fatty acid is to hydrolyze methyl ester of the medium-chain fatty acid under certain conditions, and then the medium-chain fatty acid can be obtained after hydrolysis. In the hydrolysis of medium-chain fatty acid methyl esters, it has been found that it takes a long time (24 to 72 hours) to completely hydrolyze fatty acid methyl esters to fatty acids, and that the production efficiency is low.
CN102776067A discloses a process for purifying crude fatty acid methyl ester by molecular distillation, which comprises subjecting crude fatty acid methyl ester to three-stage molecular distillation in a high vacuum molecular distillation system to extract low, medium and high carbon fatty acid methyl esters, respectively, and finally obtaining the residual plant pitch.
CN104087412A discloses a refining process and equipment of fatty acid methyl ester, which are used for obtaining biodiesel with high purity and high yield.
Yellow morning bud ("isolation of polyunsaturated fatty acid methyl esters", 2015) study Using Ag+Complexing with unsaturated fatty acid methyl ester pi electron pair to obtain AgNO3Dissolved inAn extracting agent is formed in an aqueous solution containing methanol, methyl linolenate is extracted and separated from mixed fatty acid methyl ester, and the influence of the extraction temperature, the silver ion concentration and the methanol concentration on the extraction balance and the extraction selectivity of the methyl linolenate is researched.
The method is characterized in that the method researches solvent crystallization fractionation of methyl palmitate in fatty acid methyl ester by using the rekalant (a tallow biodiesel byproduct, namely methyl palmitate fractionation development and application', 2007), and preliminary tests and solubility parameter calculation results show that ethanol is a good solvent for separating methyl palmitate, and the fractionated product is higher in purity and better in quality. At the final crystallization temperature of 1:2 and 10 ℃, methyl palmitate with the purity of 91.2 percent is obtained by ethanol separation, and after twice fractionation, the purity is 96.9 percent and the yield is 50.8 percent.
Royal jelly and the like (the gradient cooling urea clathration method for separating fatty acid methyl ester, the fine petrochemical industry, 2011, 28 (5): 23-28) adopt the gradient cooling urea clathration method for separating the biodiesel into two products of clathrated fatty acid methyl ester and non-clathrated fatty acid methyl ester. The experiment investigates the influence of factors such as temperature reduction rate, cooling stirring speed, urea/methyl ester ratio, solvent/methyl ester ratio, final cooling temperature and the like on the separation effect. Under the optimal condition, the yield of the non-inclusion fatty acid methyl ester is 83.8 percent, and the mass fraction of the unsaturated fatty acid methyl ester is 94.8 percent.
CN105154225A discloses a dry fractionation method of illegal cooking oil fatty acid methyl ester, which comprises the steps of putting mixed illegal cooking oil fatty acid methyl ester liquid to be fractionated into a crystallization tank with a stirrer, slowly cooling and stirring, freezing and crystallizing, inputting mixed methyl ester slurry into a diaphragm filter press by adopting a two-stage single-screw pump for filter pressing, collecting filtrate, sending the filtrate into an unsaturated fatty acid methyl ester tank for storage, blowing compressed air into an inlet of the mixed methyl ester slurry to recover and reuse the methyl ester slurry, heating and melting a saturated fatty acid methyl ester cake obtained by filter pressing, and pumping the saturated fatty acid methyl ester cake into a storage tank for storage.
There remains a need in the art for a method of separating fatty acids and fatty acid esters that allows for rapid separation of fatty acids and fatty acid esters to obtain high purity fatty acids.
Disclosure of Invention
The invention aims to quickly separate fatty acid ester from fatty acid to obtain fatty acid with higher purity.
Accordingly, in a first aspect, the present invention provides a method for separating fatty acid esters and fatty acids, the method comprising the step of allowing fatty acids in a mixture of fatty acid esters and fatty acids to crystallize, wherein the content of fatty acids in the mixture of fatty acid esters and fatty acids is 85% or more based on the total weight of fatty acid esters and fatty acids.
In one or more embodiments, the fatty acid content of the mixture of fatty acid esters and fatty acids is in the range of 85 to 95% by weight of the total fatty acid esters and fatty acids.
In one or more embodiments, the mixture of fatty acid esters and fatty acids is a hydrolysis product of fatty acid esters in which the mixture of fatty acid esters and fatty acids has a fatty acid content of greater than 85%, such as between 85 and 95%, based on the total weight of fatty acid esters and fatty acids.
In one or more embodiments, the fatty acid ester is a fatty acid methyl ester and/or a fatty acid ethyl ester.
In one or more embodiments, crystallization is carried out at a temperature below the melting point of the fatty acid and above the melting point of the fatty acid ester.
In one or more embodiments, the fatty acid ester has a melting point that differs from the melting point of the fatty acid to be isolated by more than 10 ℃, such as more than 15 ℃ or more than 20 ℃.
In one or more embodiments, the fatty acid ester has a melting point that differs from the melting point of the fatty acid to be isolated by 10 to 20 ℃.
In one or more embodiments, for fatty acids with carbon chains of 12 or less carbon atoms, crystallization occurs at between 0 ℃ and-8 ℃, preferably between-2 ℃ and-5 ℃.
In one or more embodiments, for fatty acids with carbon chains greater than 12 carbon atoms, when the fatty acid ester is a fatty acid methyl ester, the crystallization is between 25 and 50 ℃, preferably between 35 and 50 ℃.
In one or more embodiments, for fatty acids with a carbon chain greater than 12 carbon atoms, when the fatty acid ester is a fatty acid ethyl ester, the crystallization is between 10 and 50 ℃, preferably between 40 and 48 ℃.
In one or more embodiments, the crystallization is carried out with a hold time at the crystallization temperature of 0.5 to 1.5 hours.
In one or more embodiments, when two or more fatty acids and/or two or more fatty acid esters are included in the mixture of fatty acid esters and fatty acids, the crystallization temperature is below the melting point of the lowest melting fatty acid and above the melting point of the highest melting fatty acid ester.
In one or more embodiments, the mixture is directly subjected to a crystallization temperature for crystallization.
In one or more embodiments, the crystallization is performed by first maintaining an initial temperature 4-10 ℃ higher than the crystallization temperature for a period of time, then decreasing the temperature by 0.5-2.0 ℃ every 3-5 min, then gradually decreasing the temperature by 20-40 minutes until the temperature decreases by 4-10 ℃, preferably by 5-10 ℃, from the initial temperature, and then maintaining the temperature for 40-80 minutes.
In one or more embodiments, the crystallization is carried out by firstly preserving heat for a period of time at an initial temperature 7-15 ℃ higher than the crystallization temperature, then reducing the temperature by 3.0-8.0 ℃ in 8-10 min, preserving heat for 20-40 min, then reducing the temperature by 0.5-2.0 ℃ every 3-5 min, then preserving heat for 20-40 min, and gradually reducing the temperature until the temperature is reduced by 7-15 ℃, preferably by 7-12 ℃ from the initial temperature, and then preserving heat for 40-80 min.
In one or more embodiments, the fatty acid is a medium carbon chain fatty acid, and the crystallizing comprises:
the initial temperature is 2-3 ℃, and the materials are stirred and kept warm for 20-40 minutes;
cooling to 1.5-0.5 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
cooling to 1-0.5 ℃ within 3-5 minutes, and keeping the temperature of the materials for 20-40 minutes;
cooling to 0.5-1 ℃ within 3-5 minutes, and stirring and preserving heat for 20-40 minutes;
cooling to 0 ℃ to-1.5 ℃ within 3-5 minutes, stirring the materials, and keeping the temperature for 20-40 minutes;
cooling to-0.5 to-2 ℃ within 3 to 5 minutes, stirring the materials and keeping the temperature for 20 to 40 minutes;
cooling to-1 ℃ to-2.5 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
cooling to-1.5 ℃ to-3 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
and cooling to-2 ℃ to-3.5 ℃ within 3-5 minutes, and stirring and preserving heat for 40-80 minutes.
In one or more embodiments, the fatty acid is a long carbon chain fatty acid, preferably a C16 and/or C18 fatty acid, and the crystallization comprises:
the initial temperature is 50-53 ℃, and the materials are stirred and kept warm for 20-40 minutes;
cooling to 49-48 ℃ within 3-5 minutes, stirring the materials and preserving heat for 20-40 minutes;
cooling to 48-47 ℃ within 3-5 minutes, stirring the materials and preserving heat for 20-40 minutes;
cooling to 47.5-46.5 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
cooling to 47-46 ℃ within 3-5 minutes, stirring the materials and preserving heat for 20-40 minutes;
cooling to 46.5-45.5 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
cooling to 46-45 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
cooling to 45.5-44.5 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
and cooling to 45-44 ℃ within 3-5 minutes, and stirring and preserving heat for 40-80 minutes.
In one or more embodiments, the method further comprises the step of separating fatty acid crystals from the mixture.
In one or more embodiments, the fatty acid crystals are separated using suction filtration or pressure filtration.
In a second aspect, the invention provides the use of a fatty acid ester for the separation of fatty acids.
In one or more embodiments, the fatty acid ester has a melting point that differs from the melting point of the fatty acid to be isolated by more than 10 ℃, such as more than 15 ℃ or more than 20 ℃.
In one or more embodiments, the fatty acid ester has a melting point that differs from the melting point of the fatty acid to be isolated by 10 to 20 ℃.
In one or more embodiments, the fatty acid ester is a fatty acid methyl ester and/or a fatty acid ethyl ester.
In one or more embodiments, the fatty acid ester is a medium carbon chain fatty acid ester or a long carbon chain fatty acid ester, the fatty acid is a medium carbon chain fatty acid or a long carbon chain fatty acid, and the carbon chain length of the medium carbon chain fatty acid ester or long carbon chain fatty acid ester is within 6 carbon atoms, preferably within 4 carbon atoms, of the carbon chain length of the medium carbon chain fatty acid or long carbon chain fatty acid.
In one or more embodiments, the fatty acid ester is present in an amount ranging from 5 to 15% by weight of the total weight of the fatty acid ester and the fatty acid.
In one or more embodiments, the isolation is performed by crystallization.
In one or more embodiments, crystallization is carried out at a temperature below the melting point of the fatty acid and above the melting point of the fatty acid ester.
In one or more embodiments, for fatty acids with carbon chains of 12 or less carbon atoms, crystallization occurs at between 0 ℃ and-8 ℃, preferably between-2 ℃ and-5 ℃.
In one or more embodiments, for fatty acids with carbon chains greater than 12 carbon atoms, when the fatty acid ester is a fatty acid methyl ester, the crystallization is between 25 and 50 ℃, preferably between 35 and 50 ℃.
In one or more embodiments, for fatty acids with a carbon chain greater than 12 carbon atoms, when the fatty acid ester is a fatty acid ethyl ester, the crystallization is between 10 and 50 ℃, preferably between 40 and 48 ℃.
In one or more embodiments, the crystallization is carried out with a hold time at the crystallization temperature of 0.5 to 1.5 hours.
In one or more embodiments, when two or more fatty acid esters are used to separate a mixture of two or more fatty acids, the crystallization temperature is below the melting point of the lowest melting fatty acid and above the melting point of the highest melting fatty acid ester.
In one or more embodiments, the mixture is directly subjected to a crystallization temperature for crystallization.
In one or more embodiments, the crystallization is performed by first maintaining an initial temperature 4-10 ℃ higher than the crystallization temperature for a period of time, then decreasing the temperature by 0.5-2.0 ℃ every 3-5 min, then gradually decreasing the temperature by 20-40 minutes until the temperature decreases by 4-10 ℃, preferably by 5-10 ℃, from the initial temperature, and then maintaining the temperature for 40-80 minutes.
In one or more embodiments, the crystallization is carried out by firstly preserving heat for a period of time at an initial temperature 7-15 ℃ higher than the crystallization temperature, then reducing the temperature by 3.0-8.0 ℃ in 8-10 min, preserving heat for 20-40 min, then reducing the temperature by 0.5-2.0 ℃ every 3-5 min, then preserving heat for 20-40 min, and gradually reducing the temperature until the temperature is reduced by 7-15 ℃, preferably by 7-12 ℃ from the initial temperature, and then preserving heat for 40-80 min.
In one or more embodiments, the fatty acid is a medium carbon chain fatty acid, and the crystallizing comprises:
the initial temperature is 2-3 ℃, and the materials are stirred and kept warm for 20-40 minutes;
cooling to 1.5-0.5 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
cooling to 1-0.5 ℃ within 3-5 minutes, and keeping the temperature of the materials for 20-40 minutes;
cooling to 0.5-1 ℃ within 3-5 minutes, and stirring and preserving heat for 20-40 minutes;
cooling to 0 ℃ to-1.5 ℃ within 3-5 minutes, stirring the materials, and keeping the temperature for 20-40 minutes;
cooling to-0.5 to-2 ℃ within 3 to 5 minutes, stirring the materials and keeping the temperature for 20 to 40 minutes;
cooling to-1 ℃ to-2.5 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
cooling to-1.5 ℃ to-3 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
and cooling to-2 ℃ to-3.5 ℃ within 3-5 minutes, and stirring and preserving heat for 40-80 minutes.
In one or more embodiments, the fatty acid is a long carbon chain fatty acid, preferably a C16 and/or C18 fatty acid, and the crystallization comprises:
the initial temperature is 50-53 ℃, and the materials are stirred and kept warm for 20-40 minutes;
cooling to 49-48 ℃ within 3-5 minutes, stirring the materials and preserving heat for 20-40 minutes;
cooling to 48-47 ℃ within 3-5 minutes, stirring the materials and preserving heat for 20-40 minutes;
cooling to 47.5-46.5 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
cooling to 47-46 ℃ within 3-5 minutes, stirring the materials and preserving heat for 20-40 minutes;
cooling to 46.5-45.5 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
cooling to 46-45 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
cooling to 45.5-44.5 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
and cooling to 45-44 ℃ within 3-5 minutes, and stirring and preserving heat for 40-80 minutes.
In one or more embodiments, the separating further comprises the step of separating fatty acid crystals from the mixture.
In one or more embodiments, the fatty acid crystals are separated using suction filtration or pressure filtration.
Detailed Description
The present inventors have found that when a certain amount of fatty acid ester is present in the process of separating fatty acid, the fatty acid ester can be used as a solvent to recrystallize fatty acid, thereby completing the present invention.
Herein, the fatty acid may be a medium-chain fatty acid known in the art, i.e., a fatty acid with a carbon chain length of 6 to 12 carbon atoms, or a long-chain fatty acid, i.e., a fatty acid with a carbon chain length of 14 carbon atoms or more. In certain embodiments, the fatty acid of the present invention is a saturated fatty acid.
Herein, the fatty acid ester may be a medium-chain fatty acid ester known in the art, i.e., an ester of a fatty acid having a carbon chain of 6 to 12 carbon atoms, or a long-chain fatty acid ester, i.e., an ester of a fatty acid having a carbon chain of 14 carbon atoms or more. In certain embodiments, the fatty acid esters of the present invention are esters of saturated fatty acids. Preferably, the fatty acid ester of the present invention is a fatty acid methyl ester and/or a fatty acid ethyl ester.
The invention uses fatty acid ester as solvent of fatty acid, and separates fatty acid from fatty acid ester in liquid state by recrystallization to crystallize fatty acid. Thus, the temperature of crystallization can be determined according to the melting point of the fatty acid to be separated and the fatty acid ester used. The melting points of some of the fatty acids and fatty acid esters are listed in table 1 below:
table 1: melting Point (. degree.C.) of fatty acids and fatty acid esters having different carbon chain lengths
| Fatty acids | Fatty acid methyl ester | Fatty acid ethyl ester | |
| C8:0 | 16 | -40 | -47 |
| C10:0 | 27 | -14 | -20 |
| C12:0 | 45 | 5 | -10 |
| C14:0 | 52 | 18 | -10 |
| C16:0 | 61 | 28 | 25 |
| C18:0 | 65 | 38 | 35 |
Therefore, in general, the fatty acid may be separated using a fatty acid ester whose melting point differs from that of the fatty acid to be separated by 10 ℃ or more, and preferably, the fatty acid is separated using a fatty acid ester whose melting point differs from that of the fatty acid to be separated by 15 ℃ or more or 20 ℃ or more. In certain embodiments, the fatty acid is isolated using a fatty acid ester having a melting point that differs from the melting point of the fatty acid to be isolated by 10 to 20 ℃.
For example, to isolate C8:0 fatty acids, C8:0 fatty acid methyl ester, C8:0 fatty acid ethyl ester, C10:0 fatty acid methyl ester, C10:0 fatty acid ethyl ester, C12:0 fatty acid methyl ester, C12:0 fatty acid ethyl ester, and/or C14:0 fatty acid ethyl ester may be used. To isolate the C10:0 fatty acids, C10:0 fatty acid methyl ester, C10:0 fatty acid ethyl ester, C12:0 fatty acid methyl ester, C12:0 fatty acid ethyl ester, and/or C14:0 fatty acid ethyl ester may be used. If C18:0 is to be isolated, fatty acid methyl esters and/or fatty acid ethyl esters of C8:0 to C18:0 can be used.
If a mixture of several fatty acids is to be separated, the crystallization temperature should be below the melting point of the lowest melting fatty acid and above the melting point of the highest melting fatty acid ester. In the case where the mixture contains a plurality of fatty acids and fatty acid esters, the crystallization may be performed using the melting point temperature of the target fatty acid as the target temperature. If the melting points of the fatty acid and the fatty acid ester in the mixture are similar, the operation is considered to be carried out by adopting a multi-step crystallization and fractionation mode.
In certain embodiments, for fatty acids with a carbon chain of 12 or less carbon atoms, crystallization occurs at between 0 ℃ and-8 ℃, preferably between-2 ℃ and-5 ℃. In certain embodiments, for fatty acids with a carbon chain greater than 12 carbon atoms, when the fatty acid ester is a fatty acid methyl ester, the crystallization is between 25 and 50 ℃, preferably between 35 and 50 ℃. In certain embodiments, for fatty acids with a carbon chain greater than 12 carbon atoms, when the fatty acid ester is a fatty acid ethyl ester, the crystallization is between 10 and 50 ℃, preferably between 40 and 48 ℃.
And when the crystallization is carried out, the heat preservation time at the crystallization temperature is 0.5-1.5 hours.
In certain embodiments, the crystallization of the present invention comprises a step-down crystallization process. For example, the temperature is maintained for a period of time (e.g., 20 to 40 minutes) at an initial temperature 4 to 10 ℃ higher than the crystallization temperature, then the temperature is gradually reduced, e.g., reduced by 0.5 to 2.0 ℃ every 3 to 5 minutes, then the temperature is maintained for 20 to 40 minutes, then reduced by 0.5 to 2.0 ℃, and then maintained for 20 to 40 minutes until the temperature is reduced by 4 to 10 ℃, preferably 5 to 10 ℃ from the initial temperature, and then maintained for 40 to 80 minutes. This mode of crystallization can be used to separate medium and long chain fatty acids.
In some embodiments, the crystallization is carried out by first maintaining the temperature at an initial temperature 7-15 ℃ higher than the crystallization temperature for a period of time, then decreasing the temperature by 3.0-8.0 ℃ for 8-10 min, then decreasing the temperature by 0.5-2.0 ℃ every 3-5 min after maintaining the temperature for 20-40 min, and then gradually decreasing the temperature by maintaining the temperature for 20-40 min until the temperature decreases by 7-15 ℃, preferably by 7-12 ℃ from the initial temperature, and then maintaining the temperature for 40-80 min. This mode of crystallization can be used to separate, for example, long carbon chain fatty acids, especially C16 and C18 fatty acids.
After the crystallization is complete, the crystals can be isolated by methods customary in the art, for example suction filtration and/or pressure filtration. For example, in some embodiments, the solid-liquid mixture after crystallization is subjected to suction filtration at low temperature, and a certain pressure is applied to the filter cake. After suction filtration, the liquid is fatty acid methyl ester, and the solid is the required fatty acid.
The present invention has found that when the fatty acid content of the mixture of fatty acids and fatty acid esters is above 85%, for example 85-95%, based on the total weight of fatty acids and fatty acid esters, the fatty acids and fatty acid esters can be separated by recrystallization. When the mixture contains a plurality of fatty acids, the content of the fatty acids is the sum of the contents of all the fatty acids.
In certain embodiments, the mixture is from a hydrolysate of a fatty acid ester. Therefore, when the fatty acid ester is hydrolyzed, the hydrolysis rate is controlled so that the content of fatty acid in the hydrolyzate is 85% or more, for example, 85 to 95% by weight based on the total weight of fatty acid and fatty acid ester, and then the separation of fatty acid from fatty acid ester is achieved by the recrystallization method. The hydrolysis may be carried out by means conventional in the art. For example, a certain amount of fatty acid ester and water are taken into a container, stirred uniformly at a required temperature, then a certain amount of enzyme liquid (based on the mass of methyl ester) is added, the vacuum degree of the system is set to about 45mbar by a diaphragm pump, and the mixture is condensed, refluxed, reacted for a certain time and then kept stand for layering (if layering is not obvious, separation is carried out by a centrifugal mode). The AV can be determined by upper layer sampling for calculation of the hydrolysis rate.
The process of the invention is also suitable for the isolation of other sources of products containing the fatty acids to be isolated. In this case, the corresponding fatty acid ester may be added to the product so that the fatty acid content is above 85%, for example between 85 and 95%, based on the total weight of fatty acid and fatty acid ester contained in the product, and then the separation of fatty acid and fatty acid ester is achieved by a recrystallization process. The type of fatty acid ester to be added to the product may be selected according to the fatty acid to be separated in the product. Typically, as previously described, the melting point of the added fatty acid ester differs from the melting point of the fatty acid to be separated by more than 10 ℃, e.g. more than 15 ℃, more than 20 ℃, more than 25 ℃ or more than 30 ℃. For example, in certain embodiments, the melting point of the added fatty acid ester differs from the melting point of the fatty acid to be separated by 10 to 20 ℃.
Generally, in the present invention, the fatty acid carbon chain length of the fatty acid ester used for separating the fatty acid is within 6 carbon atoms, preferably within 4 carbon atoms, from the carbon chain length of the fatty acid. For medium-chain fatty acids or long-chain fatty acids, the fatty acid carbon chain length of the medium-chain fatty acid ester or long-chain fatty acid ester used is within 6 carbon atoms, preferably within 4 carbon atoms, of the carbon chain length of the medium-chain fatty acid or long-chain fatty acid to be separated; preferably, the separation according to the invention is carried out using the methyl or ethyl ester of the fatty acid to be separated.
The method uses the mixture of fatty acid ester and fatty acid as a substrate, changes the fatty acid into solid through slow freezing crystallization, and then carries out suction filtration or filter pressing on the solid fatty acid and the fatty acid methyl ester which are still liquid, thereby separating the fatty acid from the fatty acid ester. The purity of the fatty acid can be improved from 89% to 99% by the method.
The invention therefore also relates to the use of fatty acid esters for the separation of fatty acids. The fatty acid esters and fatty acids are as described previously.
The present invention will be illustrated below by way of specific examples. It should be understood that these implementations are merely illustrative and are not intended to limit the scope of the invention.
The medium chain fatty acid methyl esters (C810ME) used in the examples were purchased from shogazel industries (hong kong) limited and have the specific fatty acid composition: 0 percent of C6, 53.09 percent of C8, 46.72 percent of C10, 0 percent of C12 and 0.02 percent of C3878.
The enzyme solution is Lipase RML and is purchased from Nuoweixin (China) investment Limited company.
The saturated fatty acid is stearic acid, and is purchased from chemical reagents of national drug group, Inc.
The acid value detection method is determined according to GB/T5530-1998;
the calculation method of the hydrolysis rate comprises the following steps:
AV0acid value of methyl finger octyl decanoatetMeans that the acid value, AV, is sampled at a certain time interval tTheoretical valueAcid value when methyl caprylate/caprate is completely hydrolyzed. In this experiment, AV0Is 0.24mgKOH/g, AVTheoretical valueIt was 357 mgKOH/g.
All other methods and materials in the examples, unless otherwise indicated, are conventional in the art.
Preparation example
Weighing 30g C810ME and 60g of pure water in a 250mL round-bottom flask, uniformly stirring at the required temperature, adding 3% of enzyme liquid (in terms of the mass of methyl ester), setting the vacuum degree of a system to be 45mbar by using a diaphragm pump, carrying out condensation reflux reaction for a certain time, standing for layering (if layering is not obvious, separation is carried out by a centrifugal mode), and sampling the upper layer to determine AV for calculating the hydrolysis rate.
Comparative example 1
The medium-chain fatty acid methyl ester having a degree of hydrolysis of 60% (i.e., fatty acid purity of 60%, the same applies hereinafter) and the fatty acid mixture prepared in the preparation example were taken, stirred at 50rpm, and allowed to stand at-2 ℃ for crystallization, and no crystal was precipitated after standing for 1 hour.
Comparative example 2
The mixture of medium-chain fatty acid methyl ester and fatty acid with hydrolysis degree of 80% prepared in the preparation example is taken, stirred at 50rpm and placed at the temperature of-2 ℃ for crystallization, and no crystal is separated out after being placed for 1 h.
Comparative example 3
The mixture of medium-chain fatty acid methyl ester and fatty acid with hydrolysis degree of 80% prepared in the preparation example is taken, stirred at 50rpm and placed at the temperature of-5 ℃ for crystallization, and no crystal is separated out after being placed for 1 h.
Comparative example 4
Taking the mixture of the medium-chain fatty acid methyl ester with the hydrolysis degree of 60 percent and the fatty acid prepared in the preparation example, and stirring at 50rpm, adopting the following crystallization method to crystallize:
the initial temperature is 2 ℃, and the materials are stirred and kept warm for 30 min;
then cooling to 1.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 1 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 0.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 0 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to-0.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to-1 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to-1.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
finally, the temperature is reduced to-2 ℃ within 5min, and the materials are stirred and kept warm for 1 h.
No crystal precipitation occurred in the final product.
Example 1
Taking the mixture of the medium-carbon chain fatty acid methyl ester with the hydrolysis degree of 89% and the fatty acid prepared in the preparation example, stirring at 50rpm, placing at-2 ℃ for crystallization, standing for 1h to precipitate crystals, performing pressure filtration and separation to obtain a mixture of C8:0 and C10:0, and measuring the purity of the fatty acid in the mixture to be 97% and the yield of the fatty acid to be more than or equal to 80%.
Example 2
Taking the mixture of the medium-carbon chain fatty acid methyl ester with the hydrolysis degree of 87 percent and the fatty acid prepared in the preparation example, stirring at 50rpm, placing at the temperature of-2 ℃ for crystallization, standing for 1h to precipitate crystals, separating by pressure filtration to obtain a mixture of C8:0 and C10:0, and measuring the purity of the fatty acid in the mixture to be 94 percent and the yield of the fatty acid to be more than or equal to 80 percent.
Example 3
Taking the mixture of the medium-carbon chain fatty acid methyl ester with the hydrolysis degree of 88% and the fatty acid prepared in the preparation example, stirring at 50rpm, placing at-2 ℃ for crystallization, standing for 1h to precipitate crystals, separating by pressure filtration to obtain a mixture of C8:0 and C10:0, and measuring the purity of the fatty acid in the mixture to be 96% and the yield of the fatty acid to be more than or equal to 80%.
Example 4
Taking the medium-chain fatty acid methyl ester with the hydrolysis degree of 89% and the fatty acid mixture prepared in the preparation example, and stirring at 50rpm, carrying out crystallization by adopting the following crystallization method:
the initial temperature is 2 ℃, and the materials are stirred and kept warm for 30 min;
then cooling to 1.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 1 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 0.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 0 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to-0.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to-1 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to-1.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
finally, the temperature is reduced to-2 ℃ within 5min, and the materials are stirred and kept warm for 1 h.
The final product has crystal precipitation, and is separated after pressure filtration to obtain a mixture of C8:0 and C10:0, wherein the purity of fatty acid in the mixture is measured to be 98 percent, and the yield of the fatty acid is more than or equal to 80 percent.
Example 5
Taking the mixture of the medium-chain fatty acid methyl ester with the hydrolysis degree of 86% and the fatty acid prepared in the preparation example, and stirring at 50rpm, carrying out crystallization by adopting the following crystallization method:
the initial temperature is 2 ℃, and the materials are stirred and kept warm for 30 min;
then cooling to 1.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 1 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 0.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 0 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to-0.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to-1 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to-1.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
finally, the temperature is reduced to-2 ℃ within 5min, and the materials are stirred and kept warm for 1 h.
The final product has crystal precipitation, and is separated after pressure filtration to obtain a mixture of C8:0 and C10:0, the purity of fatty acid in the mixture is measured to be 97%, and the yield of the fatty acid is more than or equal to 80%.
Example 6
Taking the mixture of the medium-chain fatty acid methyl ester with the hydrolysis degree of 88 percent and the fatty acid prepared in the preparation example, and stirring at 50rpm, adopting the following crystallization method to crystallize:
the initial temperature is 2 ℃, and the materials are stirred and kept warm for 30 min;
then cooling to 1.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 1 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 0.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 0 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to-0.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to-1 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to-1.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
finally, the temperature is reduced to-2 ℃ within 5min, and the materials are stirred and kept warm for 1 h.
The final product has crystal precipitation, and is separated after pressure filtration to obtain a mixture of C8:0 and C10:0, wherein the purity of fatty acid in the mixture is measured to be 98 percent, and the yield of the fatty acid is more than or equal to 80 percent.
Example 7
Taking a mixture with a saturated fatty acid (stearic acid) content of 20-30% (stearic acid content 24.07%, oleic acid content 60.69%, linoleic acid content 10.21%, other 5.03%), adding 15% (relative to the weight of the mixture) of medium-carbon chain fatty acid methyl ester, and carrying out crystallization by adopting the following crystallization method under stirring at 50 rpm:
the initial temperature is 50 ℃, and the materials are stirred and kept warm for 30 min;
then cooling to 49 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 48 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 47.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 47 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 46.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 46 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 45.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
finally, the temperature is reduced to 45 ℃ within 5min, and the materials are stirred and kept warm for 1 h.
The final product has crystal precipitation, and is subjected to filter pressing to obtain a product with the main component of saturated fatty acid (stearic acid), wherein the content of the fatty acid in the product is measured to be 96.8%, and the yield of the fatty acid is more than or equal to 80%.
Example 8
Taking a mixture with a saturated fatty acid (stearic acid) content of 20-30% as described in example 7 (stearic acid content 24.07%, oleic acid content 60.69%, linoleic acid content 10.21%, other 5.03%), adding 12% (by weight of the mixture) of methyl esters of medium-chain fatty acids, and carrying out crystallization with stirring at 50rpm using the following crystallization method:
the initial temperature is 50 ℃, and the materials are stirred and kept warm for 30 min;
then cooling to 47 ℃ within 10min, stirring the materials and keeping the temperature for 30 min;
then cooling to 46 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 45.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 45 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 44.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 44 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 43.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
finally, the temperature is reduced to 43 ℃ within 5min, and the materials are stirred and kept warm for 1 h.
The final product has crystal precipitation, and is subjected to filter pressing to obtain a product with the main component of saturated fatty acid (stearic acid), wherein the content of the fatty acid in the product is measured to be 98.4%, and the yield of the fatty acid is more than or equal to 80%.
Example 9
Taking a mixture with a saturated fatty acid (stearic acid) content of 20-30% as described in example 7 (stearic acid content 24.07%, oleic acid content 60.69%, linoleic acid content 10.21%, other 5.03%), adding 10% (relative to the weight of the mixture) of methyl esters of medium-carbon fatty acids, and carrying out crystallization with stirring at 50rpm using the following crystallization method:
the initial temperature is 50 ℃, and the materials are stirred and kept warm for 30 min;
then cooling to 45 ℃ within 10min, stirring the materials and keeping the temperature for 30 min;
then cooling to 44 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 43.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 43 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 42.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 42 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 41.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
finally, the temperature is reduced to 41 ℃ within 5min, and the materials are stirred and kept warm for 1 h.
The final product has crystal precipitation, and is subjected to filter pressing to obtain a product with the main component of saturated fatty acid (stearic acid), wherein the content of the fatty acid in the product is 99.1 percent, and the yield of the fatty acid is more than or equal to 80 percent.
Example 10
Taking a mixture with a saturated fatty acid (stearic acid) content of 20-30% as described in example 7 (stearic acid content 24.07%, oleic acid content 60.69%, linoleic acid content 10.21%, other 5.03%), adding 11% (relative to the weight of the mixture) of methyl esters of medium-carbon fatty acids, and carrying out crystallization with stirring at 50rpm using the following crystallization method:
the initial temperature is 50 ℃, and the materials are stirred and kept warm for 30 min;
then cooling to 42 ℃ within 10min, stirring the materials and keeping the temperature for 30 min;
then cooling to 41 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 40.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 40 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 39.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 39 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then cooling to 38.5 ℃ within 5min, stirring the materials and keeping the temperature for 30 min;
then the temperature is reduced to 38 ℃ within 5min, and the materials are stirred and kept warm for 1 h.
The final product has crystal precipitation, and is subjected to filter pressing to obtain a product with the main component of saturated fatty acid (stearic acid), wherein the content of the fatty acid in the product is 99.0 percent, and the yield of the fatty acid is more than or equal to 80 percent.
Claims (35)
1. A method for separating a fatty acid ester and a fatty acid, comprising the step of allowing the fatty acid in a mixture of the fatty acid ester and the fatty acid to crystallize, wherein the content of the fatty acid in the mixture of the fatty acid ester and the fatty acid is 85% or more based on the total weight of the fatty acid ester and the fatty acid; wherein the fatty acid is a medium-carbon-chain fatty acid and/or a long-carbon-chain fatty acid, the fatty acid ester is a fatty acid methyl ester and/or a fatty acid ethyl ester, and the fatty acid in the fatty acid ester is a medium-carbon-chain fatty acid and/or a long-carbon-chain fatty acid; wherein the melting point of the fatty acid ester is different from the melting point of the fatty acid by more than 10 ℃, and the carbon chain length of the fatty acid ester is different from the carbon chain length of the fatty acid by less than 6 carbon atoms;
wherein the crystallization is carried out at a temperature lower than the melting point of the fatty acid and higher than the melting point of the fatty acid ester; when the mixture of fatty acid esters and fatty acids contains two or more fatty acids and/or two or more fatty acid esters, the crystallization temperature is lower than the melting point of the fatty acid with the lowest melting point and higher than the melting point of the fatty acid ester with the highest melting point.
2. The method of claim 1, wherein the fatty acid ester and fatty acid mixture has a fatty acid content in the range of 85 to 95%.
3. The method of claim 1, wherein the mixture is derived from a hydrolysate of fatty acid esters, wherein the hydrolysate has a fatty acid content of greater than 85% by weight of fatty acids and fatty acid esters, based on the total weight of fatty acids and fatty acid esters.
4. The method of claim 1, wherein the fatty acid ester has a melting point that differs from the melting point of the fatty acid by more than 15 ℃.
5. The method of claim 1, wherein the melting point of the fatty acid ester is different from the melting point of the fatty acid by more than 20 ℃.
6. The method of claim 1, wherein the fatty acid ester has a melting point that differs from the melting point of the fatty acid by 10 to 20 ℃.
7. The method of claim 1, wherein the fatty acid carbon chain length of the fatty acid ester is within 4 carbon atoms of the carbon chain length of the fatty acid.
8. The method of claim 1, wherein the fatty acid with a carbon chain of 12 or less carbon atoms is crystallized at a temperature between 0 ℃ and-8 ℃.
9. The method of claim 8, wherein the fatty acid having a carbon chain of 12 or less carbon atoms is crystallized at a temperature of between-2 ℃ and-5 ℃.
10. The method of claim 1, wherein for fatty acids with a carbon chain greater than 12 carbon atoms, the fatty acid ester crystallizes between 25 ℃ and 50 ℃ when the fatty acid ester is a fatty acid methyl ester.
11. The method of claim 10, wherein for fatty acids with a carbon chain greater than 12 carbon atoms, the fatty acid ester crystallizes between 35 ℃ and 50 ℃ when the fatty acid ester is a fatty acid methyl ester.
12. The method of claim 1, wherein for fatty acids with a carbon chain greater than 12 carbon atoms, when the fatty acid ester is a fatty acid ethyl ester, the crystallization is between 10 ℃ and 50 ℃.
13. The method of claim 12, wherein for fatty acids with a carbon chain greater than 12 carbon atoms, when the fatty acid ester is a fatty acid ethyl ester, the crystallization is between 40 ℃ and 48 ℃.
14. The method according to claim 1, wherein the crystallization is carried out while maintaining the temperature at the crystallization temperature for 0.5 to 1.5 hours.
15. The method of any one of claims 1-7,
(1) directly placing the mixture at a crystallization temperature for crystallization; or
(2) Firstly, preserving heat for a period of time at an initial temperature 4-10 ℃ higher than the crystallization temperature, then reducing the temperature by 0.5-2.0 ℃ every 3-5 min, then gradually reducing the temperature in a heat preservation way for 20-40 minutes until the temperature is reduced by 4-10 ℃ from the initial temperature, and then preserving heat for 40-80 minutes, thereby carrying out crystallization; or
(3) The crystallization is carried out by firstly preserving heat for a period of time at an initial temperature which is 7-15 ℃ higher than the crystallization temperature, then reducing the temperature by 3.0-8.0 ℃ in 8-10 min, preserving heat for 20-40 min, then reducing the temperature by 0.5-2.0 ℃ every 3-5 min, then gradually reducing the temperature in a way of preserving heat for 20-40 min until the temperature is reduced by 7-15 ℃ from the initial temperature, and then preserving heat for 40-80 min.
16. The method of claim 15,
in the step (2), the temperature is reduced by 5-10 ℃ from the initial temperature;
in the step (3), the temperature is reduced by 7-12 ℃ from the initial temperature.
17. The method of claim 1,
the fatty acid is a medium carbon chain fatty acid, and the crystallization comprises:
the initial temperature is 2-3 ℃, and the materials are stirred and kept warm for 20-40 minutes;
cooling to 1.5-0.5 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
cooling to 1-0.5 ℃ within 3-5 minutes, and keeping the temperature of the materials for 20-40 minutes;
cooling to 0.5-1 ℃ within 3-5 minutes, and stirring and preserving heat for 20-40 minutes;
cooling to 0 ℃ to-1.5 ℃ within 3-5 minutes, stirring the materials, and keeping the temperature for 20-40 minutes;
cooling to-0.5 to-2 ℃ within 3 to 5 minutes, stirring the materials and keeping the temperature for 20 to 40 minutes;
cooling to-1 ℃ to-2.5 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
cooling to-1.5 ℃ to-3 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
cooling to-2 ℃ to-3.5 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 40-80 minutes; or
The fatty acid is a long carbon chain fatty acid, and the crystallization comprises:
the initial temperature is 50-53 ℃, and the materials are stirred and kept warm for 20-40 minutes;
cooling to 49-48 ℃ within 3-5 minutes, stirring the materials and preserving heat for 20-40 minutes;
cooling to 48-47 ℃ within 3-5 minutes, stirring the materials and preserving heat for 20-40 minutes;
cooling to 47.5-46.5 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
cooling to 47-46 ℃ within 3-5 minutes, stirring the materials and preserving heat for 20-40 minutes;
cooling to 46.5-45.5 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
cooling to 46-45 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
cooling to 45.5-44.5 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
and cooling to 45-44 ℃ within 3-5 minutes, and stirring and preserving heat for 40-80 minutes.
18. The method of claim 17, wherein the long carbon chain fatty acid is a C16 and/or C18 fatty acid.
19. The use of fatty acid esters for the separation of fatty acids; wherein the fatty acid is a medium-carbon-chain fatty acid and/or a long-carbon-chain fatty acid, the fatty acid ester is a fatty acid methyl ester and/or a fatty acid ethyl ester, and the fatty acid in the fatty acid ester is a medium-carbon-chain fatty acid and/or a long-carbon-chain fatty acid;
the content of the fatty acid ester is 5-15% of the total weight of the fatty acid to be separated and the fatty acid ester used for separating the fatty acid;
wherein the melting point of the fatty acid ester is different from the melting point of the fatty acid by more than 10 ℃, and the carbon chain length of the fatty acid ester is different from the carbon chain length of the fatty acid by less than 6 carbon atoms;
wherein the crystallization is carried out at a temperature lower than the melting point of the fatty acid and higher than the melting point of the fatty acid ester; when the mixture of fatty acid esters and fatty acids contains two or more fatty acids and/or two or more fatty acid esters, the crystallization temperature is lower than the melting point of the fatty acid with the lowest melting point and higher than the melting point of the fatty acid ester with the highest melting point.
20. Use according to claim 19, wherein the mixture is derived from the hydrolysis product of fatty acid esters, wherein the hydrolysis product has a fatty acid content of more than 85% based on the total weight of fatty acid and fatty acid ester.
21. The use of claim 19, wherein the fatty acid ester has a melting point that differs from the melting point of the fatty acid by more than 15 ℃.
22. The use of claim 19, wherein the fatty acid ester has a melting point that differs from the melting point of the fatty acid by more than 20 ℃.
23. The use according to claim 19, wherein the fatty acid ester has a melting point which differs from the melting point of the fatty acid by 10 to 20 ℃.
24. The use of claim 19, wherein the fatty acid ester has a fatty acid carbon chain length that is within 4 carbon atoms of the carbon chain length of the fatty acid.
25. Use according to claim 19, wherein the fatty acid with a carbon chain of 12 or less carbon atoms is crystallized at a temperature between 0 ℃ and-8 ℃.
26. Use according to claim 25, wherein the crystallization is between-2 ℃ and-5 ℃.
27. Use according to claim 19, wherein for fatty acids with a carbon chain of more than 12 carbon atoms, the fatty acid ester crystallizes between 25 and 50 ℃ when it is a fatty acid methyl ester.
28. Use according to claim 27, wherein the crystallization is between 35 and 50 ℃.
29. Use according to claim 19, wherein for fatty acids with a carbon chain of more than 12 carbon atoms, the fatty acid ester crystallizes between 10 and 50 ℃ when it is an ethyl fatty acid ester.
30. Use according to claim 29, wherein the crystallization is between 40 and 48 ℃.
31. Use according to claim 19, wherein the crystallization is carried out with a holding time at the crystallization temperature of 0.5 to 1.5 hours.
32. The use according to claim 19,
(1) directly placing the mixture at a crystallization temperature for crystallization; or
(2) Firstly, preserving heat for a period of time at an initial temperature 4-10 ℃ higher than the crystallization temperature, then reducing the temperature by 0.5-2.0 ℃ every 3-5 min, then gradually reducing the temperature in a heat preservation way for 20-40 minutes until the temperature is reduced by 4-10 ℃ from the initial temperature, and then preserving heat for 40-80 minutes, thereby carrying out crystallization; or
(3) The crystallization is carried out by firstly preserving heat for a period of time at an initial temperature which is 7-15 ℃ higher than the crystallization temperature, then reducing the temperature by 3.0-8.0 ℃ in 8-10 min, preserving heat for 20-40 min, then reducing the temperature by 0.5-2.0 ℃ every 3-5 min, then gradually reducing the temperature in a way of preserving heat for 20-40 min until the temperature is reduced by 7-15 ℃ from the initial temperature, and then preserving heat for 40-80 min.
33. The use according to claim 32,
in the step (2), the temperature is reduced by 5-10 ℃ from the initial temperature;
in the step (3), the temperature is reduced by 7-12 ℃ from the initial temperature.
34. The use according to claim 19,
the fatty acid is a medium carbon chain fatty acid, and the crystallization comprises:
the initial temperature is 2-3 ℃, and the materials are stirred and kept warm for 20-40 minutes;
cooling to 1.5-0.5 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
cooling to 1-0.5 ℃ within 3-5 minutes, and keeping the temperature of the materials for 20-40 minutes;
cooling to 0.5-1 ℃ within 3-5 minutes, and stirring and preserving heat for 20-40 minutes;
cooling to 0 ℃ to-1.5 ℃ within 3-5 minutes, stirring the materials, and keeping the temperature for 20-40 minutes;
cooling to-0.5 to-2 ℃ within 3 to 5 minutes, stirring the materials and keeping the temperature for 20 to 40 minutes;
cooling to-1 ℃ to-2.5 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
cooling to-1.5 ℃ to-3 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
cooling to-2 ℃ to-3.5 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 40-80 minutes; or
The fatty acid is a long carbon chain fatty acid, and the crystallization comprises:
the initial temperature is 50-53 ℃, and the materials are stirred and kept warm for 20-40 minutes;
cooling to 49-48 ℃ within 3-5 minutes, stirring the materials and preserving heat for 20-40 minutes;
cooling to 48-47 ℃ within 3-5 minutes, stirring the materials and preserving heat for 20-40 minutes;
cooling to 47.5-46.5 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
cooling to 47-46 ℃ within 3-5 minutes, stirring the materials and preserving heat for 20-40 minutes;
cooling to 46.5-45.5 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
cooling to 46-45 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
cooling to 45.5-44.5 ℃ within 3-5 minutes, stirring the materials and keeping the temperature for 20-40 minutes;
and cooling to 45-44 ℃ within 3-5 minutes, and stirring and preserving heat for 40-80 minutes.
35. The use of claim 34, wherein the fatty acid is a long chain fatty acid that is a C16 and/or C18 fatty acid.
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| CN101177392A (en) * | 2007-12-05 | 2008-05-14 | 中国科学院新疆理化技术研究所 | Method for preparing 9,10-dihydroxystearic acid and its methyl by hydrogen dioxide oxidation process |
| CN101381297A (en) * | 2008-10-09 | 2009-03-11 | 浙江工业大学 | Method for separating caprylic acid from mixture of caprylic acid and capric acid |
| CN102408324A (en) * | 2010-09-20 | 2012-04-11 | 如皋市双马化工有限公司 | Process for purifying high-purity oleic acid |
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| CN101177392A (en) * | 2007-12-05 | 2008-05-14 | 中国科学院新疆理化技术研究所 | Method for preparing 9,10-dihydroxystearic acid and its methyl by hydrogen dioxide oxidation process |
| CN101381297A (en) * | 2008-10-09 | 2009-03-11 | 浙江工业大学 | Method for separating caprylic acid from mixture of caprylic acid and capric acid |
| CN102408324A (en) * | 2010-09-20 | 2012-04-11 | 如皋市双马化工有限公司 | Process for purifying high-purity oleic acid |
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